The present invention is generally directed to toner compositions and to imaging processes thereof. More specifically, the present invention relates to improved toner compositions and imaging processes thereof, comprising, for example, electrically conductive core particles overcoated or encapsulated with an electrically insulating material. The coated particles have well defined conductivity properties and developability properties as, for example, in single and two component xerographic developers. The toners and developers of the present invention provide a simple and effective solution to the problem of high adhesion attributable to non-uniform surface charge distributions encountered, for example, in conventional single and two component electrophotographic development materials. Furthermore, the conductive core effectively maximizes the polarizability of the toner particles so that the electrorheological cohesion of the toner particles in the direction of the applied electric field is significantly enhanced. The cohesion is highly desirable for multilayer toner transfer in process color printing systems.
The maximized polarization effect due to the conductive core can also significantly reduce the lateral attraction between toner particles of opposite charge polarities as desired in some development processes where toner in the image area and that in the background area are to be separated according to their charge polarities, for example, as in contact electrostatic printing methodologies, reference the aforementioned copending application U.S. Pat. No. 08/883,292 now U.S. Pat. No. 5,826,147.